J/AJ/158/223 RR Lyrae members of the Pal 5 stellar stream (Price-Whelan+, 2019)
Kinematics of the Palomar 5 stellar stream from RR Lyrae stars.
Price-Whelan A.M., Mateu C., Iorio G., Pearson S., Bonaca A., Belokurov V.
<Astron. J., 158, 223 (2019)>
=2019AJ....158..223P 2019AJ....158..223P (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular ; Stars, variable ;
Parallaxes, trigonometric ; Proper motions ; Photometry, ugriz ;
Stars, distances
Keywords: Globular star clusters - RR Lyrae variable stars -
Milky Way stellar halo - Milky Way dynamics
Abstract:
Thin stellar streams, formed from the tidal disruption of globular
clusters, are important gravitational tools, sensitive to both global
and small-scale properties of dark matter. The Palomar 5 stellar stream
(Pal 5) is an exemplar stream within the Milky Way: its ∼20° tidal
tails connect back to the progenitor cluster, and the stream has been used
to study the shape, total mass, and substructure fraction of the dark
matter distribution of the Galaxy. However, most details of the phase-space
distribution of the stream are not fully explained, and dynamical models
that use the stream for other inferences are therefore incomplete. Here
we aim to measure distance and kinematic properties along the Pal 5 stream
in order to motivate improved models of the system. We use a large catalog
of RR Lyrae-type stars (RRLs) with astrometric data from the Gaia mission
to probabilistically identify RRLs in the Pal 5 stream. RRLs are useful
because they are intrinsically luminous standard candles and their
distances can be inferred with small relative precision (∼3%). By building
a probabilistic model of the Pal 5 cluster and stream in proper motion
and distance, we find 27 RRLs consistent with being members of the cluster
(10) and stream (17). Using these RRLs, we detect gradients in distance
and proper motion along the stream, and provide an updated measurement
of the distance to the Pal 5 cluster using the RRLs, d=20.6±0.2 kpc.
We provide a catalog of Pal 5 RRLs with inferred membership probabilities
for future modeling work.
Description:
The PanSTARRS-1 (PS1) catalog of RRLs (Sesar et al. 2017, J/ApJ/844/L4)
contains 229K stars spanning ∼3/4 of the sky (all-sky north of decl.
δ>-30°), with multi-epoch grizy data up to a limiting magnitude
r∼21 (corresponding to G∼21 for the typical colors of RRLs). Out of the
229K RRLs in the PS1 catalog, ∼60K are also reported as RRLs by Gaia DR2
(Gaia Collaboration et al. 2018, Cat. I/345), the vast majority of which
(49K) are part of the subset defined by Sesar et al. (2017, J/ApJ/844/L4)
as bona fide.
The full PS1 RRL catalog was cross-matched with Gaia DR2, using a 1"
sky separation tolerance, in order to retrieve astrometric information
for these stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 306 3300 RRL members of the Pal 5 stream
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See also:
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/817/73 : QSOs and RR Lyrae in Pan-STARRS1 3π Data (Hernitschek+ 2016)
J/ApJ/823/157 : LOS velocities + [Fe/H] of Pal 5 tidal stream (Ishigaki+, 2016)
J/AJ/153/204 : RR Lyrae stars from the PS1 3π survey (Sesar+, 2017)
J/ApJ/842/120 : Large spectrosc. survey of Palomar 5 stellar stream
(Ibata+, 2017)
J/ApJ/844/L4 : PS1 RRab stars for tracing outer Virgo overdensity
(Sesar+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- SolID Solution Identifier in Gaia DR2 (Cat. I/345)
(solution_id)
21- 48 A28 --- DR2Name Unique source designation
(Gaia DR2 NNNNNNNNNNNNNNNNNNN) (designation)
50- 64 F15.11 deg RAdeg Gaia DR2 barycentric right ascension (ICRS)
at Ep=2015.5 (ra)
66- 72 F7.4 mas e_RAdeg Standard error of RAdeg (ra_error)
74- 88 F15.11 deg DEdeg Gaia DR2 barycentric declination (ICRS)
at Ep=2015.5 (column added by the CDS)
90- 95 F6.4 mas e_DEdeg Standard error of DEdeg (column added by
the CDS)
97-103 F7.4 mas Plx [-3.7566/2.6275] Gaia DR2 parallax (parallax)
105-110 F6.4 mas e_Plx [0.022/2.387] Standard error of Plx
(parallax_error)
112-118 F7.3 mas/yr pmRA [-27.093/10.244] Gaia DR2 proper motion in
right ascension direction (pmRA*cosDE) (pmra)
120-124 F5.3 mas/yr e_pmRA [0.028/4.194] Standard error of pmRA
(pmra_error)
126-132 F7.3 mas/yr pmDE [-25.691/9.849] Gaia DR2 proper motion in
declination direction (pmdec)
134-138 F5.3 mas/yr e_pmDE [0.02/2.768] Standard error of pmDE
(pmdec_error)
140-144 I5 --- ID-PS1 [19585/31485] PS1 identifier (Cat. II/349)
(ID_PS1)
146-154 F9.5 deg RAdegP PS1 Right Ascension in decimal degrees (J2000)
(ra_ps1)
156-164 F9.5 deg DEdegP PS1 Declination in decimal degrees (J2000)
(dec_ps1)
166-169 F4.2 --- S3ab [0/1] Final RRab classification score (S3ab)
171-174 F4.2 --- S3c [0/1] Final RRc classification score (S3c)
176-180 F5.2 mag DM [11.48/20.32] Distance modulus (DM)
182-191 F10.8 d Per [0.200556/0.891909] Period (P)
193-200 F8.5 --- phi0 [-0.49993/0.49996] Phase offset φ0
(phi0)
202-205 F4.2 mag gAmp [0.22/1.62] Amplitude in g band (Ag)
207-210 F4.2 mag rAmp [0.16/1.24] Amplitude in r band (Ar)
212-215 F4.2 mag iAmp [0.13/0.99] Amplitude in i band (Ai)
217-220 F4.2 mag zAmp [0.11/0.89] Amplitude in z band (Az)
222-226 F5.2 mag gmag [11.85/20.23] PS1 g band magnitude (gmag)
228-232 F5.2 mag rmag [11.95/20.38] PS1 r band magnitude (rmag)
234-238 F5.2 mag imag [12.04/20.44] PS1 i band magnitude (imag)
240-244 F5.2 mag zmag [12.13/20.46] PS1 z band magnitude (zmag)
246-248 I3 --- Tg [0/120] Best-fit g band template ID number
(Tg)
250-252 I3 --- Tr [0/119] Best-fit r band template ID number
(Tr)
254-256 I3 --- Ti [0/119] Best-fit i band template ID number
(Ti)
258-260 I3 --- Tz [0/117] Best-fit z band template ID number
(Tz)
262-266 F5.2 mag gmagmean [12.13/20.99] Mean g band magnitude (gmean)
268-272 F5.2 mag rmagmean [12.15/20.83] Mean r band magnitude (rmean)
274-278 F5.2 mag imagmean [12.2/20.78] Mean i band magnitude (imean)
280-284 F5.2 mag zmagmean [12.27/20.75] Mean z band magnitude (zmean)
286-289 A4 --- Type RR Lyrae type (RRab or RRc) (PS1_type)
291-299 F9.5 kpc Dist [2.19309/116.054] Distance (D_ps1)
301-304 F4.2 --- Memb [0/1] Membership probability (member_prob)
306 I1 --- Track [0/1] Inside stream track
(insidestreamtrack)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 23-Jan-2020